According to the American College of Obstetricians and Gynecologists, hypertensive disorders of pregnancy including preeclampsia complicate approximately 10% of pregnancies throughout the world and are a leading cause of maternal and fetal morbidity and mortality [ref: Hypertension in Pregnancy, Report of the American College of Obstetricians and Gynecologists' Task Force on Hypertension in Pregnancy, Obstetrics and Gynecology 122 Vol. 122, No. 5, November 2013 (the ACOG 2013 guildelines)]. Furthermore, these conditions are a leading cause of premature births and associated perinatal complications [ref: Ananth C V, Vintzileos A M. J Matern Fetal Neonatal Med. 2006:19(12):773-82]. Hypertension in pregnancy can be categorized as 1) preeclampsia-eclampsia, 2) chronic hypertension 3) chronic hypertension with superimposed preeclampsia or 4) gestational hypertension.
Preeclampsia-eclampsia is a poorly understood pregnancy-related condition that is a leading cause of maternal mortality, premature birth, and rising healthcare costs for maternity. Globally, the death of 76,000 expectant mothers is due to preeclampsia. Preeclampsia is responsible for one-fifth of deaths related to pregnancy in the U.S., and the condition can lead to seizures, organ failure and death. It most commonly occurs after about 20 weeks of pregnancy, and women are at risk through the postpartum period. The condition can result in seizures or convulsions known as eclampsia. Preeclampsia may be categorized as mild, severe, less severe, more severe or as preeclampsia without severe features, or preeclampsia with severe features. HELLP syndrome, a preeclampsia subtype, is characterized as patients with symptoms of hemolysis, elevated liver enzymes and low platelet count. Preeclampsia that presents with an unusual compilation of symptoms is known as atypical preeclampsia.
The only known cure is to deliver the baby, and as a result, preeclampsia is the leading cause of pre-term births that are medically indicated, estimated to be 17% of all preterm births. Costs to the U.S. healthcare system are estimated to be over $13 billion for delivery and care of mother and infant due to preeclampsia. Today, preeclampsia remains a challenge to diagnose, as it is characterized only by its symptoms: most often, high blood pressure and the presence of urine protein. Research towards improving the diagnosis of preeclampsia has commonly searched for known biomarkers in blood which are up- or down-regulated, but few if any findings have yielded globally useful diagnostic products.
Research utilizing urine specimens of women with severe preeclampsia that required medically indicated delivery due to a diagnosis of preeclampsia (MIDPE) and an unbiased mass spectrometry protein profiling approach and found unique non-random cleavage products of SERPINA-1 and albumin. Knowledge of the tendency of SERPINA-1 fragments to misfold and form supramolecular aggregates led to the proposal that preeclampsia may be a misfolding disorder, not unlike Alzheimer's disease [See U.S. Pat. No. 8,263,342 and Buhimschi et al., Am J Obstet Gynecol. 2008 November; 199(5): 551.e1-551.16. doi:10.1016/j.ajog.2008.07.006.]
Furthermore, misfolded protein based on binding of the proteins to Congo Red (CR) dye (“congophilia”) were found in urine from women with preeclampsia. These misfolded protein(s) or “supramolecular aggregates” bound to conformational state-dependent anti-amyloid aggregate antibodies were associated with a highly active amyloid precursor protein (APP) processing pathway and amyloid-like protein deposits in placentas from preeclamptic women. [See Buhimschi et al., Sci. Transl. Med. 6, 245ra92 (2014).] A dot blot affinity assay measured the proportion of CR retained (due to binding to misfolded protein) after washing (as % of original CR) and results were reported as % Congo Red Retention (CRR).
In a feasibility study of 80 women (40 who required medically indicated delivery and 40 were “control” healthy pregnancies), % CRR was significantly higher in severe preeclampsia urine (P<0.001) with 100% sensitivity and specificity. In a validation study of 582 women (in cross sectional and longitudinal cohorts), women with severe preeclampsia and preeclampsia superimposed on existing high blood pressure or proteinuria had higher % CRR than all other clinical classifications (P<0.001). Furthermore, 75% of women diagnosed with mild preeclampsia, 89% with severe preeclampsia and 91% with superimposed preeclampsia had CRR results higher than all other groups (P<0.05). Overall, CRR alone in the validation cohort had 85.9% sensitivity and 85.00 specificity, positive likelihood ratio of 95% and negative likelihood ratio of 95% in prediction of preeclampsia necessitating MIDPE. CRR was superior to clinical screening methods currently used for preeclampsia (P<0.001 compared to blood pressure or urine protein dipstick; P=0.004 compared to combined blood pressure combined with urine protein at American College of Obstetricians and Gynecologists (ACOG) recommended cutoffs) (Buhimschi et al., Sci. Transl. Med. 6, 245ra92 (2014) and U.S. Pat. No. 9,229,009.)
Congo Red also binds to cellulose which was used to create a simple paper based assay. Normal urine-dye mixtures applied to test paper results in dye binding to the cellulose in the paper visualized as a red tightly centered dot. In contrast, urine from women with congophilic urine proteins results in the dye no longer binding to cellulose because it is bound to the proteins and instead dispersing in a diffuse fashion visualized as a halo. (See U.S. Patent Application Publication No. 20150293115.) In a clinical study of 346 women referred to a labor and delivery triage center to rule-out preeclampsia, patient urine was tested using the CR simple paper assay (CRD). The CRD test demonstrated a 79% sensitivity 89% specificity, negative predictive value of 91%, positive predictive value of 74% for the diagnosis of preeclampsia as defined by the ACOG 2013 guidelines [ref: Rood et al 2016 AJOG Volume 214, Issue 1, Supplement, Pages S24-S25]. The CRD test requires a step of mixing urine with dye before applying the urine to the test paper and the results can be challenging to read and interpret.
In view of the above, there is still a highly significant and unmet need for a simple diagnostic device that may be used at the point of care to detect possible preeclampsia in pregnant mammals and especially women. Such a device could potentially save the lives of thousands of pregnant women as well as their unborn fetuses by providing early information as to whether a woman is at risk for preeclampsia or has preeclampsia and should therefore receive immediate therapeutic intervention.
All patents and publications referred to herein are hereby incorporated in their entirety by reference.